1. Field of the Invention
The present invention relates to an information processing device, a communication system, and an information processing method. In particular, the present invention relates to an information processing device having a receiving unit that receives information for causing an apparatus to execute a predetermined processing, and a communication system, and an information processing method.
2. Description of the Related Art
As a conventional communication system, there is known a communication system having: a transmitting device that wirelessly transmits a request signal requesting execution of a predetermined processing with respect to an apparatus; and a receiving device that is provided at the apparatus that is the transmission destination of the transmitting device, and that receives the request signal transmitted from the transmitting device, and that causes the apparatus to execute the predetermined processing in accordance with the received request signal (see, for example, Japanese Patent Application Laid-Open (JP-A) No. 2006-108850). In this communication system, the transmitting device and the receiving device are synchronized, and, when the receiving device receives the entire request signal transmitted from the transmitted device, the receiving device notifies the apparatus that reception is completed. The apparatus receives this notification and executes the predetermined processing.
A structural example of an illuminating system 100 to which the conventional communication system is applied is shown in FIG. 1. As shown in FIG. 1, the illuminating system 100 has: an illuminating device 102 that, when a photograph is being taken, illuminates supplementary light onto a subject as needed; and an illumination instructing device 104 that, by using wireless communication, instructs the illuminating device 102 to illuminate supplementary light.
The illuminating device 102 is structured to include: a flash device 106 that emits supplementary light in accordance with an inputted instruction; a communication device 108 that carries out wireless communication with the illumination instructing device 104 via a communication network; and a control device 110 that controls the illuminating device 102 overall. The flash device 106 and the communication device 108 are connected to the control device 110. Accordingly, the control device 110 can respectively carry out access to the flash device 106 and the communication device 108, and control of the flash device 106 and the communication device 108.
The illumination instructing device 104 is structured to include: a switch 112 that is operated on when the illuminating device 102 is to be instructed to illuminate supplementary light; a communication device 114 that carries out wireless communication with the illuminating device 102 via a communication network; and a control device 116 that controls the illumination instructing device 104 overall. The switch 112 and the communication device 114 are connected to the control device 116. Accordingly, the control device 116 can respectively carry out grasping of whether or not the switch 112 has been operated on, access to the communication device 114, and control of the communication device 114.
When the switch 112 is operated on, the illumination instructing device 104 that is structured in this way generates information to be processed that is to be processed at the illuminating device 102 and that is digital data that includes illumination instruction information that instructs the illuminating device 102 to illuminate supplementary light. The illumination instructing device 104 wirelessly transmits the generated information to be processed to the illuminating device 102. Note that the aforementioned “instruction to illuminate supplementary light” includes an instruction to start charging, an instruction to stop charging, and an instruction to start illumination of the supplementary light (an instruction to discharge), with respect to the flash device 106.
An example of the information to be processed that is wirelessly transmitted from the illumination instructing device 104 to the illuminating device 102 is shown in FIG. 2. As shown in FIG. 2, the information to be processed is formed from digital data that is stored in a frame for serial transmission (e.g., an IEEE 802.3 frame), and is structured by digital data that are a preamble, an SFD (Start Frame Delimiter), data length, an address, illumination instruction information, and a CRC (Cyclic Redundancy Check) being lined-up in series from the head to the tail of the frame.
The preamble is a synchronization code that is added to the start of the information to be processed, and is a bit string that is used in order to calibrate the device that is used in wirelessly receiving the information to be processed and in demodulating the information to be processed that is obtained by wireless reception. The SFD is an identifying bit string for enabling identification of the end of the preamble, and is a bit string expressing that the data that follows thereafter is the valid data (the data length, the address, the illumination instruction information and the CRC) among the information to be processed. The data length is a parameter expressing the range (length) of the valid data, i.e., the data among the information to be processed other than the preamble and the SFD. The address is the MAC address that is uniquely assigned to the illumination instructing device 102 serving as the sender, and the MAC address that serves as identifying information that is uniquely assigned to the illuminating device 102 serving as the recipient. The CRC is a code for detecting errors in the valid data.
A structural example of the communication device 108 is shown in FIG. 3. Although the communication device 114 also is structured similarly, here, the communication device 108 is described as an example. As shown in FIG. 3, the communication device 108 is structured to include a control circuit 118, a modulator 120, a demodulator 122, an RF (Radio Frequency) device 124, and an interface circuit 126.
The control circuit 118 controls the communication device 108 overall. The modulator 120 modulates the data that is inputted from the previous stage, and outputs the modulated data to the following stage. The demodulator 122 converts inputted analog data into digital data, and outputs the digital data. The RF device 124 is set in a transmittable state, a receivable state, or a stopped state in accordance with an inputted instruction. In the transmittable state, the RF device 124 converts inputted digital data into RF signals, and transmits the signals from an antenna. In the receivable state, the RF device 124 converts RF signals received at the antenna into analog signals, and outputs the analog signals. Further, the interface circuit 126 is for carrying out transmission and receipt of information between the control device 110 and the control circuit 118.
The modulator 120, the demodulator 122 and the control circuit 118 are connected to the RF device 124. The control circuit 118 is connected to the modulator 120 and the demodulator 122. The control device 110 and the control circuit 118 are connected to the interface circuit 126. Accordingly, the control circuit 118 can respectively carry out receipt of data outputted from the RF device 124 via the demodulator 122, control of the RF device 124, transmission of data to the RF device 124 via the modulator 120, and transmission and receipt of information with the control device 110 via the interface circuit 126.
A structural example of the control circuit 118 is shown in FIG. 9. As shown in FIG. 9, the control circuit 118 is structured to include a detection circuit 118A, an RX_FIFO 118B, and a transmission control circuit 118C. The detection circuit 118A is connected to the demodulator 122 and the interface circuit 126. The RX_FIFO 118B is connected to the detection circuit 118A, the demodulator 122 and the interface circuit 126. The transmission control circuit 118C is connected to the modulator 120, the RF device 124 and the interface circuit 126.
The detection circuit 118A detects the preamble, the SFD and the data length that are included in the information to be processed that is inputted from the RF device 124 via the demodulator 122, and outputs the detection results to the RF_FIFO 118B, and outputs the detection results also to the control device 110 via the interface circuit 126.
The RF_FIFO 118B is a memory that stores data, and that outputs stored data in accordance with an inputted request signal. When detection of the data length by the detection circuit 118A is started, the RF_FIFO 118B starts storing the information to be processed that is inputted from the RF device 124 via the demodulator 122. When detection of the data length by the detection circuit 118A is completed, the RF_FIFO 118B stops storage of the information to be processed, and, in accordance with a request signal inputted from the control device 110 via the interface circuit 126, outputs the stored information to be processed to the control device 110 via the interface circuit 126.
In accordance with an instruction from the control device 110 via the interface circuit 126, the transmission control circuit 118C outputs, to the RF device 124, a control signal that controls the RF device 124, and manipulates data inputted from the control device 110 via the interface circuit 126, and wirelessly transmits the manipulated data to the RF device 124 by outputting the data to the RF device 124 via the modulator 120.
Transitions of the state of the illuminating system 100 are shown in FIG. 10. As shown in FIG. 10, at the illumination instructing device 104, when the switch 112 is operated on (switch on), the control device 116 generates information to be processed, and outputs, to the communication device 114, the generated information to be processed and an RF start-up instruction signal that instructs start-up of the RF device 124. In response to the RF start-up instruction signal inputted from the control device 116, the communication device 114 starts-up the RF device 124 and sets the RF device 124 in the transmittable state. Thereafter, the communication device 114 wirelessly transmits, to the illuminating device 102, the information to be processed that has been inputted from the control device 116 (data transmission). Then, when the wireless transmission of the information to be processed is completed, the communication device 114 shifts the RF device 124 from the transmittable state to the receivable state.
At the illuminating device 102, when the power is turned on (not shown), a standby command is issued from the control device 110 to the communication device 108. In accordance with the standby command inputted from the control device 110, the communication device 108 starts-up the RF device 124 and sets the RF device 124 in the receivable state. Thereafter, the communication device 108 awaits receipt of the information to be processed that is to be transmitted from the illumination instructing device 104. When transmission of the information to be processed from the illumination instructing device 104 is started, the communication device 108 continues to receive the information to be processed until the transmission of the information to be processed is completed. The communication device 108 stores the received information to be processed in the RX_FIFO 118B. Then, when receipt of the information to be processed is completed, the communication device 108 shifts the RF device 124 from the receivable state to the transmittable state, and starts wireless transmission, to the illumination instructing device 104, of an Ack response packet that expresses that data receipt has been competed normally. When the wireless transmission of the Ack response packet is completed, the communication device 108 shifts the RF device 124 from the transmittable state to the stopped state.
When transmission of the Ack response packet from the illuminating device 102 is started, the communication device 114 of the illumination instructing device 104 continues to receive the Ack response packet until transmission of the Ack response packet is completed. Then, when receipt of the Ack response packet is completed, the communication device 114 shifts the RF device 124 from the receivable state to the stopped state, and thereafter, outputs, to the control device 116, a transmission completion notification signal that gives notice that transmission to the illuminating device 102 of the information to be processed has been completed. The control device 116 receives the transmission completion notification signal inputted from the communication device 114.
After the communication device 108 shifts the RF device 124 from the transmittable state to the stopped state, the communication device 108 outputs, to the control device 110, a receipt completion notification signal that gives notice that receipt of the information to be processed has been completed. In response to the receipt completion notification signal inputted from the communication device 108, the control device 110 outputs a request signal to the communication device 108. In response to the request signal inputted from the control device 110, the communication device 108 transfers, to the control device 110, the information to be processed that has been already received. The control device 110 analyzes the information to be processed that has been inputted from the communication device 108, and judges whether or not the address of the information to be processed and its own address match. If the addresses match, the control device 110 instructs the flash device 106 to start charging. The flash device 106 receives the instruction to start charging from the control device 110, and starts charging. When a predetermined time period (e.g., the time period for the charged amount to reach a predetermined amount) has passed from the giving of the instruction to the flash device 106 to start charging, the control device 110 instructs the flash device 106 to stop charging, and causes the flash device 106 to start illumination of supplementary light.
However, in the illuminating system 100, the illuminating device 102 cannot illuminate supplementary light until after all of the information to be processed, that is transmitted from the illumination instructing device 104, has been received. Therefore, the illuminating system 100 cannot be applied to cases in which a rapid response is required, such as in cases in which supplementary light is illuminated when taking photos. Note that a rapid response is also required of liquid crystal shutter glasses that are used when viewing stereoscopic video, to which attention is being given recently. Thus, application of the communication system that is applied to the illuminating system 100 is difficult.
Generally, in apparatuses in which synchronization is needed at times of transmission and receipt and in which a rapid response is required, such as the illuminating device 102 of the illuminating system 100 or liquid crystal shutter glasses or the like, improvement in the amount of information that is processed per unit time (called “throughput” hereinafter) is needed.
The technique disclosed in JP-A No. 2001-306487 is known as a technique for improving throughput. This technique discloses a computer that gives notice of interruption of transmission of data from a transmitting-side processor unit to a receiving-side processor unit that has a data processing mechanism. When the receiving-side processor unit receives an interruption signal transmitted from the transmitting-side processor unit, the receiving-side processor unit starts-up the data processing mechanism. When the receiving-side processor unit receives a data transmission end notification signal that is transmitted from the transmitting-side processor unit, processing of data transmitted from the transmitting-side processor unit is started by the data processing mechanism. In accordance with this technique, because processing of data can be started before data transmission is completed, high throughput can be realized as compared with a conventional communication system.
However, in the technique of JP-A No. 2001-306487, the interruption signal must be transmitted from the transmitting-side processor unit to the receiving-side processor unit separately from the data that is to be processed. Therefore, other planned processings thereafter are delayed by an amount corresponding to the time required for executing the processing for generating and transmitting and receiving the interruption signal.